1. Field of Invention
The invention relates to an apparatus for producing bags from tubular material comprising fabric made of stretched plastic strips. The apparatus has at least one tube-forming device or a tube-unwinding device, by which tubular material, for producing bar can be produced from web-shaped material and in which the tubular material can he conveyed in a transport direction (x′), and at least one tube-separating device, by which tube pieces can be separated from the tubular material, and a bottom-forming device, by which bottoms can be molded onto at least one end of a tube piece, and at least one transport device for transporting the tube pieces within the bottom-forming device in a transport direction (x) extending transversely to their direction of extension (y). The invention also relates to a method of producing bags from web-shaped material with the help of at least one tube-forming device or a tube-unwinding device. In the method, the tubular material is conveyed in a transport direction (x′), and tube pieces are separated from the tubular material with the help of at least one tube-separating device. Bottoms are molded onto at least one of a tube piece in a bottom-forming device, and the tube pieces are transported within the bottom-forming device with the help of at least one transport device in a transport direction (x) extending transversely to the direction of extension (y) of the tube pieces.
2. Description of the Prior Art
Such apparatuses are known in the prior art and have been available on the market for quite a while now. These apparatuses usually first comprise a tube-forming device for producing and providing tubular material. Provision can also be made for only a tube-unwinding device. This device can usually be equipped with a spool, on which tubular material is wound. The material is mostly drawn off continuously from this spool in the longitudinal direction.
In the bag-making process carried out on machines known in the prior art, the fabric tube provided by the tube-forming device or the tube-unwinding device is supplied to the cross cutter that separates the fabric tube into individual tube pieces. The tube pieces are transferred to a transport device. The original transport direction, in which the tube or the tube pieces are transported in the direction of their longitudinal axes, is altered with the help of this transport device to a new transport direction so that the tube pieces are no longer transported in the direction of their longitudinal axes, but instead transversely thereto so that the ends of the tube pieces can be reached laterally for the purpose of molding the bottoms. The original and the new transport directions of the tube or the tube piece are located at right angles to each other.
As mentioned above, the tubular fabric material that can additionally be coated is separated into tube pieces. When producing the tube pieces, the tube is drawn cyclically in its longitudinal direction by the length of each tube piece. In order to enable the cyclical drawing of the tube, there is a compensating device provided in the form of at least one movable deflecting rod provided between the spool of material and the separating device. A tube piece is then isolated, thus separated, from the tube. This step is usually carried out by means of a cutting tool such as a blade. Other separation processes and the associated devices are also feasible. The aforementioned spool of material often comprises a fabric tube made of circular woven material. The tube produced on a circular loom is collapsed after its production and provided with a coating that ensures that portions of the tube piece can be heat-sealed together without damaging the stretched fabric and affecting its strength adversely.
The tube-forming device molds tubular material in that the edges of the material web are placed on top of each other and joined together, for example, by means of a plastic extrusion. In this process, both the flat material web and the tube are transported in the longitudinal direction. The tubular material is made of two superimposed material webs, each of which can comprise a number of layers. The aforementioned tube-forming device can further be able to insert side gussets. Bags provided with side gussets are advantageous when they are to be stacked in the filled state. The major advantage in producing tubes from woven and coated flat material is that coating material does not protrude laterally over the edges of the flat tube, as is often the case when collapsed, circular woven tubular material is coated. Protruding coating material frequently results in errors when producing bags from pieces of the tubular material.
The tube piece produced in the manner described above is received by at least one transport device in order to deliver them to the individual processing stations. After being separated from the tubular material, the tube pieces are no longer transported further in the longitudinal direction, but instead in the transverse direction. The term “transverse direction” is understood to mean that the tube pieces are now transported in a direction extending transversely to their longitudinal extension in order to obtain unobstructed access to both ends of the tube pieces in the further steps carried out for producing bags.
The individual processing stations used in the bag-making process are listed below together with an explanation of their functions.                In an optionally provided pre-creasing station, form punches are lowered onto the tube piece for producing fold lines. The turned-in corners of the opened tube bottom will later be located on these fold lines. The form punches can also be heated for this purpose.        In the bottom-opening station, at least one end of a tube piece is raised so that a bottom can be molded onto this raised end. The turned-in corners are located on the fold lines of the tube piece. Due to its geometric shape, the bottom opening is also called the bottom square. It should be noted here that the shape of the bottom opening is not square, but rectangular in most cases. Both ends of a tube piece are usually processed in a similar manner.        In the valve patch station, a valve patch is applied to the previously opened bottom of the tube piece. The valve patch enables the finished bag to be filled later with the help of a suitable fill nozzle.        In a so-called closing station, parts of the bottom openings or the bottom squares, the so-called tabs, are folded back on both sides toward the folded edge. In doing so, portions of these tabs can overlap each other, and these overlapping portions of these tabs can be joined together.        A bottom patch is then attached, for example heat-sealed to the folded bottom opening in the bottom patch station.        
It should be mentioned here that all the stations listed above need not be present in an apparatus for producing bags. It is thus possible to dispense with a pre-creasing station. It is also not required to always apply bottom patches in order to produce a bag. Nonetheless, the apparatus may also comprise additional processing stations. As mentioned above, in the bag-making process carried out on bag-making apparatuses known in the prior art, the fabric tube provided by the tube-forming device is supplied to the cross cutter that separates the fabric tube into individual tube pieces. The tube pieces are transferred to a transport device. The original transport direction, in which the tube or the tube pieces are transported in the direction of their longitudinal axes, is altered with the help of this transport device to a new transport direction so that the tube pieces are no longer transported in the direction of their longitudinal axes, but instead transversely thereto so that the ends of the tube pieces can be reached laterally for the purpose of molding the bottoms. The original and the new transport direction of the tube or the tube piece are located at right angles to each other. It is for this reason that the tube-forming device and the aforementioned processing stations are also disposed or set up so as to extend at right angles to each other.
The arrangement of the tube-forming device so as to extend at right angles to the processing stations is disadvantageous. The floor space of production halls is usually rectangular, and therefore such an arrangement of devices takes up space.